FreeBSD: zfs commands backward compatibility

Update the zfs commands such that they're backwards compatible with
the version of ZFS is the base FreeBSD.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Ryan Moeller <[email protected]>
Signed-off-by: Matt Macy <[email protected]>
Closes #10542 

2 files changed, 64 insertions, 8 deletions

diff --git a/lib/libzutil/Makefile.am b/lib/libzutil/Makefile.am
index bbd69b780..cd03ba19d 100644
--- a/lib/libzutil/Makefile.am
+++ b/lib/libzutil/Makefile.am
@@ -23,10 +23,16 @@ USER_C += \
 endif
 
 if BUILD_FREEBSD
+DEFAULT_INCLUDES += -I$(top_srcdir)/include/os/freebsd/zfs
+
 USER_C += \
 	os/freebsd/zutil_device_path_os.c \
 	os/freebsd/zutil_import_os.c \
 	os/freebsd/zutil_compat.c
+
+VPATH += $(top_srcdir)/module/os/freebsd/zfs
+
+nodist_libzutil_la_SOURCES = zfs_ioctl_compat.c
 endif
 
 libzutil_la_SOURCES = $(USER_C)
diff --git a/lib/libzutil/os/freebsd/zutil_compat.c b/lib/libzutil/os/freebsd/zutil_compat.c
index 5b0fe8548..3e70fef1e 100644
--- a/lib/libzutil/os/freebsd/zutil_compat.c
+++ b/lib/libzutil/os/freebsd/zutil_compat.c
@@ -20,15 +20,35 @@
  */
 #include <sys/types.h>
 #include <sys/param.h>
+#include <sys/sysctl.h>
 #include <sys/zfs_ioctl.h>
 #include <os/freebsd/zfs/sys/zfs_ioctl_compat.h>
 #include <libzutil.h>
 
+#include <err.h>
+
+int zfs_ioctl_version = ZFS_IOCVER_UNDEF;
+
+/*
+ * Get zfs_ioctl_version
+ */
+static int
+get_zfs_ioctl_version(void)
+{
+	size_t ver_size;
+	int ver = ZFS_IOCVER_NONE;
+
+	ver_size = sizeof (ver);
+	sysctlbyname("vfs.zfs.version.ioctl", &ver, &ver_size, NULL, 0);
+
+	return (ver);
+}
+
 static int
 zcmd_ioctl_compat(int fd, int request, zfs_cmd_t *zc, const int cflag)
 {
-	int ret;
-	void *zc_c;
+	int newrequest, ret;
+	void *zc_c = NULL;
 	unsigned long ncmd;
 	zfs_iocparm_t zp;
 
@@ -37,17 +57,32 @@ zcmd_ioctl_compat(int fd, int request, zfs_cmd_t *zc, const int cflag)
 		ncmd = _IOWR('Z', request, zfs_iocparm_t);
 		zp.zfs_cmd = (uint64_t)zc;
 		zp.zfs_cmd_size = sizeof (zfs_cmd_t);
-		zp.zfs_ioctl_version = ZFS_IOCVER_ZOF;
-		return (ioctl(fd, ncmd, &zp));
+		zp.zfs_ioctl_version = ZFS_IOCVER_OZFS;
+		break;
+	case ZFS_CMD_COMPAT_LEGACY:
+		newrequest = zfs_ioctl_ozfs_to_legacy(request);
+		ncmd = _IOWR('Z', newrequest, zfs_iocparm_t);
+		zc_c = malloc(sizeof (zfs_cmd_legacy_t));
+		zfs_cmd_ozfs_to_legacy(zc, zc_c);
+		zp.zfs_cmd = (uint64_t)zc_c;
+		zp.zfs_cmd_size = sizeof (zfs_cmd_legacy_t);
+		zp.zfs_ioctl_version = ZFS_IOCVER_LEGACY;
+		break;
 	default:
 		abort();
 		return (EINVAL);
 	}
 
-	ret = ioctl(fd, ncmd, zc_c);
-	zfs_cmd_compat_get(zc, (caddr_t)zc_c, cflag);
-	free(zc_c);
-
+	ret = ioctl(fd, ncmd, &zp);
+	if (ret) {
+		if (zc_c)
+			free(zc_c);
+		return (ret);
+	}
+	if (zc_c) {
+		zfs_cmd_legacy_to_ozfs(zc_c, zc);
+		free(zc_c);
+	}
 	return (ret);
 }
 
@@ -62,6 +97,21 @@ zfs_ioctl_fd(int fd, unsigned long request, zfs_cmd_t *zc)
 	size_t oldsize;
 	int ret, cflag = ZFS_CMD_COMPAT_NONE;
 
+	if (zfs_ioctl_version == ZFS_IOCVER_UNDEF)
+		zfs_ioctl_version = get_zfs_ioctl_version();
+
+	switch (zfs_ioctl_version) {
+		case ZFS_IOCVER_LEGACY:
+			cflag = ZFS_CMD_COMPAT_LEGACY;
+			break;
+		case ZFS_IOCVER_OZFS:
+			cflag = ZFS_CMD_COMPAT_NONE;
+			break;
+		default:
+			errx(1, "unrecognized zfs ioctl version %d",
+			    zfs_ioctl_version);
+	}
+
 	oldsize = zc->zc_nvlist_dst_size;
 	ret = zcmd_ioctl_compat(fd, request, zc, cflag);